Mahbod Moghadam, the co-founder of Rap Genius, has resigned from the Web text annotation startup after making insensitive comments about the massacre earlier this week in Santa Barbara, Calif., that left seven dead, including the killer.

Moghadam's resignation came after he made annotations Saturday on the site to the 141-page manifesto of Elliot Rodger, who killed six people around the Isla Vista community on Friday before taking his own life. Moghadam's annotations were intended to make the text easier to understand, but they "not only didn't attempt to enhance anyone's understanding of the text, but went beyond that into gleeful insensitivity and misogyny," Tom Lehman, a fellow Rap Genius co-founder and its chief executive, wrote in a statement Sunday.

The since-deleted comments, first written about by Valleywag, called portions of Rodger's manifesto "artful" and "beautifully written" and suggested that "his sister is smokin' hot."

Moghadam later apologized for the comments, telling Valleywag that he was "fascinated by the fact that a text was associated with such a heartbreaking crime, especially since Elliot is talking about my neighborhood growing up."

"I got carried away with making the annotations and making any comment about his sister was in horrible taste, thankfully the rap genius community edits out my poor judgement, I am very sorry for writing it," he said.

Lehman called Moghadam a friend who has "a ton of love in his heart" and said Rap Genius wouldn't exist without his contribution.

"But I cannot let him compromise the Rap Genius mission -- a mission that remains almost as delicate and inchoate as it was when we three founders decided to devote our lives to it almost 5 years ago," Lehman wrote.

Rap Genius was founded in 2009 by Moghadam, Lehman, and Ilan Zechory on the idea that rap lyrics needed explanation. The New York-based company got a $15 million investment in 2012 from venture capital firm Andreessen Horowitz.